6x45 Terrible ES numbers

[GrocMax]

Here, I found an updated version 8.1-

https://drive.google.com/file/d/0Bzuroq2iOSD7S2JDRFFYMFQtRTg/view

 

[shortgrass]

Winchester 748 lit by a Win.SRP did the trick for me. The bullet is a 80g Blitz, all loaded into a Winchester case. Velocity spread for 10rds is in single digits. Barrel is a Hart 1-10 twist screwed on to a Winchester 70.

 

[swd]

I use H4895 and Ball C2 with heavier 80-95gr bullets in mine. Both shoot well. CFE was fast but never accurate. H335 would be worth a try with light bullets.

 

[expiper]

what do the groups look like,,,,Roger

 

[fredo]

OK, since chrono passed muster...

What is the neck diameter of your chamber?
What is the nk. diameter of your loaded rounds?
If you're on the tight side of clearance, could be pressure is spiking in certain rounds, but not others. That would lead to wild velocity swings, such as what you're seeing...

How are you seating bullets in relation to the lands?
If you're in the 'just kissing the lands' area, then, due to misc. variances (bullet, dies, press, etc.), one bullet might be jammed & the next one might be jumping. That would also affect pressure & result in spikey velocity...

Finally, how are you throwing charges and what are you weighing them with?
Make double sure that the charge weights are consistent & accurate...

Of the three 6x45s I've loaded for, plus my current 6x45AI, have experienced no issues with huge velocity spread. That's with 5-6 different powders, three different primers, and 5 different kinds of .223Rem parent brass.

If you've got access to other brass, try the same loads with a different brand & see what you get. If spread is still way huge, I'd start scrutinizing that barrrel...

 

[CharlieNC]

What was your load development procedure? Is the es across the board, or due to a flyer or two? With that high es I tend to think you need to try something altogether different vs tweaking.

 

[rebel]

Lake City brass, annealed. RCBS FL sizer, Forster micrometer seater. Best results with IMR 3031 and N133. 133 gives slower velocity, but a smidge better numbers. I use a CCI 450 primer. Have a 20 inch AR with a Shilen 5r barrel and a 24 inch X-caliber barreled M7. Both shoot 1/4 MOA if I do my part. The 24 inch bolt shoots 87 gr VLDs at around 2750 with the 133. I'm happy with it. 8208 didn't do all that well for me but it might work great for you.
Keep working with it as it's good for prairie dogs to whitetails. Lot's of fun.

 

[John from MN]

One thing I've noticed with my setup, is that brass comes out of die with a somewhat rounded shoulder. Headspace during the initial fireforming varies quite a bit from case to case. My loads are stiff enough to form the brass to a uniform dimension during the first firing, but if they were not, I could imagine it causing issues similar to what the OP is experiencing. My money is on this or neck tension issues.

Good luck. It's a heck of a little round and I don't think the troubles you are having are the norm. Don't get discouraged.